Modify Amplify CLI Generated Cloudformation File to Support a GraphQL Interface

modifyAmplifyCF.js

/** 
 * Example script to change amplify cli-generated cloudformation stack to support a graphql interface. See https://github.com/aws-amplify/amplify-cli/issues/202. 
 * Run this before every amplify push command (e.g. create your own bash script that does something like: amplify api gql-compile && node ./scripts/modifyAmplifyCF.js && ./amplify/backend/api/<your_app_name>/build/cloudformtion-template.json && amplify push --no-gql-override)
 * Everytime you run amplify api gql-compile, the cloudformation files will be overwritten and this script would need to be run again. 
 *
 * As an example for this script, it assumes you have a custom User table built (through custom stacks - User.json for the AppSync resolvers and UserTable.json for the dynamodb table) and a Doctor and Patient model that implement this interface, e.g. 
 *
 * interface User {
 *  id: ID!
 *. email: AWSEmail!
 * }
 *
 * type Doctor implements User @model {
 *  id: ID!
 *. email: AWSEmail
 *. licenseNumber: Int
 * }
 *
 * type Patient implements User @model {
 *. id: ID!
 *. email: AWSEmail
 *. healthcardNumber: Int
 * }
 */

const AWS = require('aws-sdk');
AWS.config.update({ region: '<your_region>' });
const fs = require('fs');
const path = require('path');
const fileName = process.argv[2];
const stacksDir = path.join(path.dirname(fileName), 'stacks');

run();

async function run() {

  changeDependencies(fileName);

  changeConnectionStack(path.join(stacksDir, 'ConnectionStack.json'));

  changeModelStack(path.join(stacksDir, 'Patient.json'));
  changeModelStack(path.join(stacksDir, 'Doctor.json'));

}

function changeDependencies(cfFileName) {
  const jsonFileContent = fs.readFileSync(cfFileName);
  const jsonContent = JSON.parse(jsonFileContent);

  jsonContent.Resources.UserTablejson.DependsOn = ['GraphQLSchema'];
  jsonContent.Resources.Userjson.DependsOn = ['GraphQLSchema', 'UserTablejson'];
  jsonContent.Resources.Doctor.DependsOn = ['GraphQLSchema', 'Userjson'];
  jsonContent.Resources.Patient.DependsOn = ['GraphQLSchema', 'Userjson'];

  delete jsonContent.Resources.Doctorjson;

  fs.writeFileSync(fileName, JSON.stringify(jsonContent, null, 2));

  console.log(`Updated ${cfFileName}`);
}

function changeConnectionStack(stackFileName) {
  let stackFileContent = fs.readFileSync(stackFileName, 'utf8');
  stackFileContent = stackFileContent.replace(
    /DoctorDataSource|PatientDataSource/gi,
    'UserDataSource'
  );
  fs.writeFileSync(stackFileName, stackFileContent);
  console.log(`Updated ${stackFileName}`);
}

function changeModelStack(stackFileName) {
  const stackFileContent = fs.readFileSync(stackFileName, 'utf8');
  const jsonContent = JSON.parse(stackFileContent);
  Object.keys(jsonContent.Resources).forEach(key => {
    if (key.endsWith('Resolver')) {
      jsonContent.Resources[key].Properties.DataSourceName = 'UserTable';
    } else {
      delete jsonContent.Resources[key];
    }
  });
  delete jsonContent.Outputs;
  fs.writeFileSync(stackFileName, JSON.stringify(jsonContent, null, 2));
  console.log(`Updated ${stackFileName}`);
}